Saajid Badat testified from London at the New York trial of Sulaiman Abu Ghaith, al Qaida's spokesman, immediately after the September 11 2001 attacks that demolished the World Trade Centre in New York.

The 34-year-old Briton said he was recruited in the autumn of 2001 to blow up a plane but pulled out of the plot in December 2001.

Immediately before Badat's testimony, prosecutors showed jurors videotape of Abu Ghaith warning Muslims in America and England not to board planes because he said the "storm of airplanes will not stop". Prosecutors claim the testimony shows Abu Ghaith knew of al Qaida's plans.

Abu Ghaith is charged with conspiring to kill Americans and providing material support to al Qaida.

Abu Ghaith, 48, a former imam at a Kuwaiti mosque, has pleaded not guilty in the case. He is the highest-ranking al Qaida figure to face trial on US soil since the September 11 attacks

Abu Ghaith, born in Kuwait, faces a possible life prison sentence if he is convicted of conspiring to kill Americans and of providing material support to al Qaida.

His trial began last week, a year after he was captured in Turkey and brought to the US for trial. About five years ago, he married bin Laden's eldest daughter, Fatima, and he was al Qaida spokesman after the 2001 attacks.

Badat was convicted in London in a 2001 plot to down an American Airlines flight from Paris to Miami with explosives hidden in his shoes.

In videotaped evidence shown to a jury in New York at a 2012 terrorism trial, Badat said he refused a request to testify in person in the US because he remains under indictment in Boston on charges he conspired with failed shoe-bomber Richard Reid, and he has been told he would be arrested if he set foot in the US.